Isocyanurate compounds and processes for preparing same

ABSTRACT

Phenylisocyanuric acid is reacted with acrylonitrile in the presence of N-benzyltrimethyl ammonium hydroxide; 40% in methanol, in an inert solvent at 75*C. to 150*C to produce 1,3bis(2-cyanoethyl)-5-phenylisocyanurate. The 1,3-bis(2cyanoethyl)-5-phenylisocyanurate is then heated with a mineral acid to produce 1,3-bis(2-carboxyethyl)-5-phenylisocyanurate.

United States Patent [191 Kauffman Dec. 23, 1975 [5 ISOCYANURATE COMPOUNDS AND 3,235,553 2/1966 Sadle 260/248 PROCESSES FOR PREPARING SAME 75 Inventor: William J. Kaufiman, Lititz, Pa. Primary Examiner-John M. Ford [73] Assignee: Armstrong Cork Company,

Lancaster, Pa. 22 Filed: Dec. 31, 1974 [57] ABSIRACT [21] Appl. No.: 537,687 Phenylisocyanuric acid is reacted with acrylonitrile in the presence of N.-benzyltrimethyl ammonium hydrox- '-4 t 'rt 1 tt75C.t 52 us. Cl 260/248 NS; 260/868; 260/75 N f;6O 3x1 2 i a ff z 2 7 Ifinifl} C07D 263/34 phenylisocyanurate The 1 3 i 2 h 5 1 e 0 260/248 NS phenylisocyanurate is then heated with a mineral acid 4 to produce l,3 bis(2-carboxyethyl)-5- [56] Referenms cued phenylisocyanufate.

UNITED STATES PATENTS r I 1 5/1965 Phillips et al 260/248 X 4 Claims, No Drawings ISOCYANURATE COMPOUNDS AND PROCESSES FOR PREPARING SAME CROSS-REFERENCE TO- RELATED APPLICATIONS The polyesters derived from l,3-bis(2-carboxyethyl)- 5-phenylisocyanurate' are claimed in copending US. patent application entitled Linear Isocyanu'rate Polyeste'rs and Processes for Preparing Same by William J. Kauffman, Ser. No. 537,686, filed Dec. 31, 1974.

BACKGROUND OF-TI-IE INVENTION FIELD OF THE INVENTION This invention relates to novel isocyanurate organic compounds and processes. More particularly, it relates to l,3-bis( 2-carboxyethyl)'-5-phenylisocyanurate and intermediates thereof. Additionally, it relates to certain processes related to the preparation of the above compounds.

r DESCRIPTION OF THE PRIOR ART 2 them useful in forming coatings and molded plastic articles.

DESCRIPTION OF THE PREFERRED EMBODIMENT 1,3-bis(2-carboxyethyl)-5-phenylisocyanurate is a solid dibasic carboxylic acid. It is useful in a number of applications, particularly in the preparation of its polymers such as polyesters. It is especially useful in forming coatings and molded plastic articles.

1 ,3-bis( 2-carboxyethyl )-5-phenylisocyanurate can be prepared by the cyanoethylation reaction of phenylisocyanuric acid with acrylonitrile in the presence of N-benzyltrimethyl ammonium hydroxide (40% in methanol), in an inert reaction medium to form the intermediate l,3-bis(2-cyanoethyl)-5-phenylisocyanurate. The intermediate is then hydrolyzed as by exposure to a strong mineral acid, such as concentrated hydrochloric acid to form the diacid.

While at least 2 moles of acrylonitrile to one mole of phenylisocyanuric acid is required, an excess of acrylonitrile is preferred.

Any reaction medium which is inert and which will form a suitable reaction mixture at elevated temperathyl)a5-phenylisocyanurate and its hydrolysis product produced. v

SUMMARY OF THE INVENTION,

In accordance with the present invention, it has now been discovered that l,3-bis(2-carboxyethyl)-5- phenylisocyanurate is produced by a process which l,3-bis(2-carboxyethyl)-5 phenylisocy anurate will be comprises reacting phenylisocyanuric acid with acrylonitrile in the presence'of N-benz'yltrimethyl ammonium hydroxide; 40% in' methanol, in an inert solvent to yield l,3-bis(2-cyanoethyl-)-5 phenyli'socyanurate as illustrated by the following reaction:

- N I T r T T H a tures can be used. For use in the above reaction, the lower dialkyl substituted amides of lower carboxylic acid, such as dimethylformamide, diethylformamide, and dimethylacetamide, are suitable solvents. It is preferred to employ dimethylformamide as the inert reaction medium. Y

Any tetraalkyl ammonium hydroxide compound may be added to the'reaction mixture in order to facilitate the reaction. N-benzyltrimethyl ammonium hydroxide; 40% in methanol, is the preferred tetraalkyl ammonium hydroxide compound.

The amount of tetraalkyl ammonium hydroxide present in the reaction mixture will range from about 1 to 20% by weight based on the weight of the phenylisocyanuric acid present, and preferably from about 1 to 5%.

The reaction is carried on at an elevated reaction temperature for a time sufficient to bring satisfactory yields. The acrylonitrile is added at a reasonable rate to an inert reaction medium containing phenylisocyanuric acid and N-benzyltrimethyl ammonium hydroxide; 40% in methanol, maintained at a temperature of C. to 150C., about C. usually being suitable. The reaction will be carried on for a time sufficient to ensure an adequate yield, about two to ten hours being ordinarily ample, depending upon the concentration of the reactants employed, the reaction temperature, and the like.

The l,3-bis(2-cyanoethyl)-5-phenylisocyanurate is isolated from the reaction mixture by evaporation of the inert reaction medium under reduced pressure. The intermediate compound may be further purified by recrystallization from any suitable solvent such as dimethylformamide, acetonitrile, ethanol or carbon tetrachloride.

As mentioned above, the intermediate is convertible to the desired 1,3-bis(2-carboxyethyl)-5- phenylisocyanurate by acid hydrolysis with, for example, a concentrated mineral acid such as concentrated hydrochloric acid. The hydrolysis can be conveniently effected by heating the hydrolysis mixture of the intermediate at an elevated temperature for a sufficient period of time to convert to the desired l,3-bis(2-carboxyethyl)-5-phenylisocyanurate. An hydrolysis time of about one to ten hours at reflux temperature is usually sufficientzto-bring about the desired hydrolysis with hydrochloric acid. l,3-bis(2-carboxyethyl)-5- phenylisocyanurate is recovered and isolated from the hydrolysates by following conventional procedures. Customarily, the diacid is relatively insoluble in most of the mineral acids employed for the hydrolysis, for example, in concentrated hydrochloric acid, and can be recovered from the cooled hydrolysate conveniently by following simple filtration procedures. The l,3-bis(2- carboxyethyl)--phenylisocyanurate compound can be recrystallized as desired, as from distilled water.

Usable polyesters can be formed by condensing as by heating at elevated temperatures l,3-bis(2-carboxyethyl)-5-phenylisocyanurate with the required amounts of a diol having at least two carbon atoms, and preferably two to ten carbon atoms. Suitable diols may include, for example, l,4-butanediol, l,6-hexanediol, ethylene glycol, diethylene glycol, alpha-propylene glycol, and decamethylene glycol. The relative quantities of the l,3-bis(2-carboxyethyl)-5-phenylisocyanurate and diol can be varied somewhat to alter average polymer chain links, degree of esterification. of the carboxyl groups, and the like. To form a largely linear polymer, at least about one mole of diol is applied for each mole of l ,3-bis(2-carboxyethyl)-5- phenylisocyanurate.

Polyesters made by condensing l,3-bis(carboxyethyl)-5-phenylisocyanurate with a polyol as described above exhibit excellent strength rendering them extremely useful in the preparation of coatings and molded plastic articles.

Moreover, l,3-bis(2-carboxyethyl)-5- phenylisocyanurate and the fibers derived therefrom are extremely thermally stable, and produce low smoke upon combustion.

The following illustrative examples more fully describe the preparation of the l,3-bis(2-carboxyethyl)- 5phenylisocyanurate. I

EXAMPLE 1 Preparation of l,3-bis(,2-cyanoethyl)-5-phenylisocyanurate A quantity of 25ml. of acrylonitrile (20.0 g., 0.38 mole) is added to a solution of phenylisocyanurate (20.3 g., 0.1 mole) and 5 ml. ofTriton B (40% solution of benzyltrimethyl ammonium hydroxide in methanol) in 75 ml. of dimethylformamide. The reaction mixture is heated to l20C.'and held for 2 hours. It is then cooled to room temperature, and 5 ml. of 6N hydrochloric acid is added. The mixture is concentrated on a rotary evaporator at reduced pressure yielding a viscous liquid. The viscous product is slurried with pentane and solidified upon cooling. The solid is then recrystallized from ethanol yielding 64% l,3-bis(2- cyanoethyl)-5-phenylisocyanurate (19.8 g., 0.064 ml.).

- hydrochloric acid (950 ml.), and water (.150 ml.) is

refluxed for 4 hours, and then cooled to 0C. The resulting precipitate is collected and recrystallized from water to yield (78%) l,3-bis(2-carboxyethyl)-5- phenylisocyanurate (175 g., 0.50 ml.).

EXAMPLE 2 Preparation of 1,3-bis(2-cyanoethyl)-5-phenylisocyanurate In accordance with the procedure of Example 1, 3 ml. of Triton B (benzyltrimethyl ammonium hydroxide; 40% in methanol), is added to a solution of 20.3 g. (0.1 mole) of phenylisocyanurate and ml. of dimethylformamide. To this solution, 25 ml. of acrylonitrile (20.0 g., 0.38 mole) is added overa period of forty-five minutes and the final solution is heated at reflux (C.) for 3 hours. The solution is cooled to room temperature and 5 ml. of 6N hydrochloric acid is added to acidify the mixture. The dimethylformamide and the excess acrylonitrile are evaporated off at reduced pressure. The residue is recrystallized from ethanol yielding l ,3-bis(2-cyanoethyl)-5 -phenylisocyanurate.

Preparation of l ,3-bis(2-carboxyethyl)-5-phenylisocyanurate In like fashion, to Example 1, the intermediate l,3- bis(2-cyanoethyl)-5-phenylisocyanurate is hydrolyzed by hydrochloric acid. A mixture of 200 g. of l,3-bis(2- cyanoethyl)-5-phenylisocyanurate and 950 ml. of concentrated hydrochloric acid is refluxed for four hours. The solution is cooled to 5C. and the solid filtered. Recrystallization from water yields 174 g. of l,3-bis(2- carboxyethyl)-5-phenylisocyanurate.

What is claimed is:

l. 1,3-bis(2-cyanoethyl)-5-phenylisocyanurate.

2. 1 ,3-bis( 2-carboxyethyl)-5-phenylisocyanurate.

3. A process for preparing l,3-bis( 2-carboxyethyl)-5- phenylisocyanurate comprising reacting phenylisocyanuric acid with acrylonitrile in the presence of N-benzyltrimethyl ammonium hydroxide; 40% in methanol, in an inert reaction.;medium at a temperature of about 75C. to C. to form the intermediate l,3-bis(2-cyanoethyl)-5-phenylisocyanurate, and hydrolyzing said intermediate in the presence of an acid to yield l,3-bis(2-carboxyethyl)-5-phenylisocyanurate.

4. The process in accordance with claim 3 wherein the inert reaction medium is dimethylformamide. 

1. 1,3-BIS(2-CYANOETHYL)-5-PHENYLISOCYANURATE.
 2. 1,3-bis(2-carboxyethyl)-5-phenylisocyanurate.
 3. A process for preparing 1,3-bis(2-carboxyethyl)-5-phenylisocyanurate comprising reacting phenylisocyanuric acid with acrylonitrile in the presence of N-benzyltrimethyl ammonium hydroxide; 40% in methanol, in an inert reaction medium at a temperature of about 75*C. to 150*C. to form the intermediate 1, 3-bis(2-cyanoethyl)-5-phenylisocyanurate, and hydrolyzing said intermediate in the presence of an acid to yield 1,3-bis(2-carboxyethyl)-5-phenylisocyanurate.
 4. The process in accordance with claim 3 wherein the inert reaction medium is dimethylformamide. 